Rigid piece of metal insulated against electrolysis and corrosion and the process of making the same.



. P. M. lSTEWART.' RIGID PIECE OF-METAL INSULATED AGAINST ELECTROLYSISAND CORROSION AND THE PROCESS 0F vMAKING THE SAME. A

1,167,949., Patented' Jan'. 11, 1916.

APPLICATIONYFILED SEPT. 16. 1912.

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- f; amarres rarnnfr einen :PEREZ M. STEWART, 0F NEW YORK, N. Y.,ASSIGNORF ONE-HALE T0 HAROLD' H. ROBERTSON, OF SEwlCKLEY, PENNSYLVANIA,AND' ONE-HALF T0 GERTBUDE F.

STEWART.

RIGID PIECE 0F METAL INSULATED AGAINST ELECTROLYSIS AND ORROSION AND THEPROCESS 0F MAKING THE SAME.

Specification of Letters Patent. Patented Jan. 11, 1916.

' Application led September 16, 1912. Serial No. 720,492.

To all 'whom it may concern:

Be it known that I, PEREZ M. STEWART, a citizen of the United States,and a resident of the borough of Manhattan, city, county,

and State of New York, have invented anL representing like parts.

This invention relates to a novel process of insulating rigid pieces ofmetal against; electrolysis and corrosion and to the productJ lofsuchprocess.

The process is especially applicable for treating large pieces ofstructural steel, such as beams, girders, etc., employed in theconstruction of buildings, bridges, and the like,

whereby said steel structures are insulated` and thereby protectedagainst electrolysis and corrosion.

Prior to this invention many methods have been devised and manycompositions have been used for coating steel, with a view to absolutelyexcludingmoisture,which it was well known, must be excluded in order toprotect steel from electrolysis and corrosion, but'these methods andcompositions havenot been successful. No paint has as yet been devisedwhich will absolutely accomplish this purpose. Linseed oil which is thevehicle for practically all paints designed for protective coatings, isrecognized by those skilled in the art to have several fatal defects.Even when the coat of linseed oil is skilfully applied, voids are boundto occur which will allow the entrance of moisture to attack the coatedsurface. In-

order to avoid this objection, pigments have water, is sealed in by thepaint in ordinary painting, thus leaving the lilm of moisture tocontinue its electrolytic action with the metal, producing rustunderneath the paint.

T he so-called protective coating of linseed oil in combination withmany of the lead and zinc pigments is not a stable compound and after acomparatively short time a chemical change analogous to saponificationtakes place. It is therefore but a brief time before moisture due tocondensation removes the oily compound leaving the pigment, which, 1nitself, is not a protective coating, and is generally a rust promoter.This is the action commonly spoken of as chalking. One of the chiefcharacteristics of pure linseed oil is the fact that it oXidizes, but itis not generally known that after this oXidation reaches a certain stagethe compound thus produced is soluble in water.

Cushman and Gardner in their recent book on Corrosion and Preservationof Iron and Steel have this to say with regard to bituminous compounds:From the standpoint of the] electrolytic theory of corrosion, it hasrepeatedly been stated in the foregoing pages that a natural insulatoror nonconductor of electricity should be Well adapted for the protectionof iron. In view v of the truth of this general principle, it would seemthat bituminous f compounds were peculiarly Well adapted for thepurpose. Unfortunately, many materials. which are well adapted for theprotection of iron from one point of view are too prone to fail fromanother. As a matter of fact, most bitumens will not stand free exposureto atmospheric conditions, water and sunlight. It is a significant factthat in the cases in which bitumens have been-successfully used, it hasbeen under conditions in 'which the material was not, so to speak,normally eX- posed to sunlight and the atmosphere. To sum up thediscussion of the use of bituminous paint and .compounds as protectivecoats for iron, the authors wish to reiterate their opinicn that inspecial cases, and if properly selected, there are no better materialsavailable.

In accordance with this invention, I have provided a method forproducing insulated structural steel shapes orA members or any steelstructure, no matter how large, in`

which the steel is insulated by a sheet or layer of asbestos paperagainst electrolysis and corrosion and in which a bituminous compositionis employed to secure the 'asbestos sheet or layer to 'the steelstructure and is protected yagainst the injurious action l'of sunlight,moisture vand evaporation on such compounds by the vsheet or layer ofasbestos, as Will be described, whereby the bituminous compositionremains in its original condition and leffective as an adhesive for anindefinite length of time.

ln accordance With the method employed by me, the steel structure iscleansed and heated, and While the steel is in a heated condition, alayer or coating of iiuxe'd phalt is applied thereto, and almost immefliately a sheet or layer of. asbestos paper is applied to the asphaltlayer, While the latter is in an adhesive fluid condition. The asfbestos sheet may -thenbe coated with paint, cement, or layers of asphaltand felt or paper.

In the accompanying vdrawing I have illustrated one form of protectedstructural steel member produced by my method and embodyingmy-invention. i

Figure l is a front vie'wof an 'll column,l

and vF ig:'2,`a transverse detail sectional view of the column shown inFig. 1 on an en-y larged scale. l

In carrying out my process, the first step of cleaning the surface ofthesteel is' preferably carried out when the structural `shape or member-isat the job, yin the fieldl` or at the place of erection.y All surfacesof the structural shape :are first thoroughly cleaned and heated. Thecleaning may be accomplished by Wire brushing, sand blasting or anylother suitable'mechanical or chemical method. The cleaning may also beaccompli'sh'edr by burning 'with' one 'or more gasolene torches or any'kind ofs'uitable gas furnace. `lli-any event thje step of burning orheating shouldvbe lused, since this removes 1shop coat, oil, scale,surface ilin, :moisture and o the'r deleterious yfactors and at the same:time heats the surface of the-member, and

bevappliedeither hot or cold but preferably hot.

The bituminous composition vfor the best' results is ali'uxed'bitumemvthat is, a high grade asphalt having a high meltingpoint, namely about 225? to 250 F., is tempered or -luxed bytheadditionof animal fats'or slovvdrying-oils, such'as stearin pitch intheproportion of from 5 'to`10%, which liu'X has'the effect of makingthebitumen more durable, tenacious, pliable", and of retaining itselasticityfo'r a 'long timef4 While the coating'of the bituminouscomposition is still seft, a-layer'or 'sheet of-as'besto's 'paper' isapplied With pressure to the coated surface of the metal structure, andthis process is repeated until the Whole of one surface of the rigidsteel member is covered by the layer of bituminous composition and thelayer or sheet of asbestos paper, which lis especially serviceable forthe purpose, for

the following reasons: (l) The `sheet of asbestos is not penetrated bythe actinic rays of the sun, which have a deleterious effect on theasphalt,.in that they take the llife out of the asphalt and render itliable to crack and expose the steel. (2) The sheet of asbestos normallycontains from seven to fourteen per cent. of Water vof its ovvn, that'is, by absorption, and in addition about four per cent. .of water ofcrystallization, and therefore vthe asphalt coating is practicallyprotected by a Wall Yof `Water in the asbestos sheet, which prevents'theoil in the asphalt from passing through the asbestos sheet and thereforeprevents evaporation of the oil and the deterioration of the asphaltcoating, Which remains unchanged for-ani'ndefinite length of time. rlheasbestos sheet'o'rlayer may be painted or otherwise treated on itseXposed surface to Waterproof it, or it may have applied to itadditional layers of bituminous composition and asbestos,- felt, lpape-ror cement.

It is preferred to protect the layer or sheet y of asbestos -With paintor other material as described, but it is 'not desired to limit theinvention in this vrespect as good -results would be obtained With theplain-asbestos sheet alone.

In the present instance, the I column show-n in the drawing is providedWith a plurality o f layers of Vbituminous composition andasbestos.

In; Fig. 2, A represents the first layer of bituminouscomposition, B thelayer of asbestos paper, C a layer of bituminous com vposition on thelayer B, D a layer of asbestos paper, E a layer of bituminouscomposition applied to the layer D, F a layerof Waterproof fabric in.the formv of prepared felt, mu slin or linen, Ga layer'of bituminouscomposition or! mastic. Theprotected I column may be embedded inconcrete or other suitable fr'eproof building material J,

ln some" instances itmay be desirableto provide'thesteel structure Witha plurality of 'layers of bituminous composition. and sheets or layersof'asbesto's, but in mostcases, it Will be s'uiicientto provide asingle'layer of' bituminous composition and a single sheet i ia or layerof asbestos, and render the latter Waterproof by, painting the exteriorsurface thereof, for in the simpler lconstruction it Will be seen thatthe steelmember istho'roughly protecte'da gainst electrolysisandcorrosion,

by the layerl of the bituminous'composition and, by the sheet ofasbestosv for the 'reasons labove set'forth 'and 'further 'by theadditional layer of paint or other waterproof material, I.Which preventsevaporation of the Water p Wall in the asbestos layer, and also prevents`moisture penetrating into the asbestos.

In some cases, as for instance in buildings, it'may be preferred toprotect all the surfaces of the steel structur or member, Whereas in thesame and other structures, such for instance as bridges and the like,

it may be found suflicient to protect only those surfaces of the steelmember which are exposed to the atmosphere. In either case, the surfaceofthe steel member covered by the bituminous composition and the sheet ior llayer of asbestos is thoroughly protected from the deleteriousVaction of extraneous `fumes, gases, atmospheric conditions and stray orground electric currents, and also from interior deterioration, that is,deterioration of the bituminous composition. Claims: 1. The process ofinsulating structural steel shapes to prevent electrolysis andcorrosion, which consists in cleaning and heat- 25. .ing the surfaces ofthe steel structure to remove scale, dirt, moisture, etc., and to openthe pores of the steel, applying to the steel structure thus cleanedandWhile in a heated 'condition a iiuxed bituminous composition,

.l applying to said coating of bituminous composition While thelatter issoft a layer of asbestosfpaper in its normal condition, and applying'to,the exterior surface of the asbestos paper a waterproofcoating, for the3.5 purpose specified.

l2. The process of insulating structural steel shapes yto preventelectrolysis and corrosion, which consists in cleaning and heat-y ingthefsurfaces of the steel structure to re- A 40n move scale,l dirt,moisture, etc., and to open the pores of the steel, applying to thesteel structure thus cleaned and while in a heated condition a iiuxedbituminous composition, and applying to said coating of bituminouscomposition While the latter is soft a paper in its normal condia` sheetof insulating material which is imprevious to sunlight and in its normalcondition. Y

4. As an improved article of manufacture,

a rigid piece of corrodible metal havingits outer surface free fromdeleterious substances protected'by alayer of bituminous compositionapplied to the ysaid surface, and penetrating into the pores thereof,and a layer of asbestos paper adhesively secured to the rigid metalstructure'by said bituminous coating which penetrates one surface of theasbestos layer, substantially as described.

5. The process of insulating a rigid piece of metal, vvhichconsists incleaning the rigid article, coating the rigid article thus treated witha layer of bituminous composition, applying to the bituminous layerWhile soft a layer of asbestos, folding the layer of asbestos about thecoated rigid article to envelop the same, and pressing the asbestoslayer into firm contact With the rigid article.

6. The process of insulating a rigid piece of metal,which consists incleaning the rigid article, coating the rigid article thus cleaned.While in a heated condition with adhesive material, applying to themetal article thus y coated and While the coating of adhesive ma- '1cured thereto by said bituminous coating which penetrates one surface ofthe asbestos layer.

8. As an improved article of manufacture,

a rigid piece of corrodible metal having its outer surfaces free fromscale, dirt, oil and moisture and protected by a layer of bituminouscomposition ,applied to the said surfaces and penetrating into the poresthereof, and a, layer of fibrous insulating material enveloping saidrigid metal structure and adhesively secured theretoby said bituminouscoating. a

9. As anwimproved article of manufacture,

a rigid piece of corrodible metal having its outer surfaces free from.deleterious substances and protected by a layer of adhesive lmaterialapplied to'said surfaces, and a layer of fibrous insulating materialenveloping said rigid structure and secured'thereto by said adhesivecoating.,

In testimony whereof, I' have signed my name to this specification inthe presence of twoy subscribing witnesses.

PEREZ M. STEWART.

